This application relates generally to rotary machines and more particularly, to apparatus and systems for sealing a rotary machine.
At least some rotary machines, such as steam turbine engines, have a defined fluid flow path extending therethrough. The flow path includes, in a serial-flow relationship, a fluid inlet, a turbine, and a fluid outlet. The process fluid may contain debris or solid particles within the system. The debris or solid particles may deposit on internal components and seals of the rotary machine, and may affect turbine engine performance.
Some rotary machines use a plurality of sealing assemblies in the flow path and endpacking regions to facilitate increasing the operating efficiency of the rotary machine. Generally, known seal assemblies are coupled between a stationary component and a rotary component to provide sealing between a high-pressure area and a low-pressure area. Several known sealing assemblies include flexible members such as brush seals, labyrinth teeth, and hydrodynamic face seals.
In some known rotary machines, hydrodynamic face seals may be used to facilitate reducing leakage of a pressurized process fluid through a gap between two components. Hydrodynamic face seals generally include a mating (rotating) ring and a seal (stationary) ring. Generally, shallow hydrodynamic grooves are formed or etched on the mating ring face. During operation, the hydrodynamic grooves in the rotating ring generate a hydrodynamic force that causes the stationary ring to lift or separate from the rotating ring such that a small gap is created between the two rings. A sealing gas flows through the gap between the rotating and stationary rings. Large debris may not be able to enter the small gap between the mating ring and seal ring; however, fine solid particles and contaminants in the process fluid may be able to enter the gap and become caught in the hydrodynamic grooves of the rotating and/or stationary rings.
In some known rotary machines, such as gas turbine engines, maintenance of face seals may be relatively straightforward. At least some known face seals in gas turbines engines may be easily disassembled from the rotating shaft and cleaned of any debris buildup. However, is some known rotary machines, such as steam turbine engines, maintenance of face seals may be challenging. At least some known steam turbine engines may be operated continuously for a period of years, thus facilitating the buildup of debris and contaminants in the grooves of the rings of the face seal. In addition, at least some known steam turbine engines are extremely large, containing rotatable shafts with diameters larger than 20 inches. Such large internal components add to the complexity of maintenance of the seals of such known steam turbine engines.